You'll find this information in the file amule.conf, check the Readme (which is included with the Mac-Binary) for the path on mac.
On Linux the file resides in the hidden directory .aMule inside your home folder.
Either open the file with a text editor and search for "TotalUploadedBytes" or use the following command (on Linux):
cat ~/.aMule/amule.conf | grep TotalUploadedBytes